SIGNIFICANT

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SIGNIFICANT FIGURES
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• All measurements are approximationsno measuring
  device can give perfect measurements without
  experimental uncertainty. By convention, a mass
  measured to 13.2 g is said to have an absolute
  uncertainty of plus or minus 0.1 g and is said to
  have been measured to the nearest 0.1 g. In other
  words, we are somewhat uncertain about that last
  digitit could be a "2" then again, it could be
  a "1" or a "3". A mass of 13.20 g indicates an
  absolute uncertainty of plus or minus 0.01 g.

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What are significant Figures?
The significant figures in a measurement Consist
of all the digits known with certainty plus one
final digit, which is uncertain or is estimated.
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Your reading might be 76 ml. But, how sure are
you that it is really 76 ml? Is it possible that
its also 75.99 or 76.01?
CERTAIN VALUE 75 UNCERTAIN VALUE 0.991.1
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What is Accuracy?

• Accuracy - a measure of how close a measurement
  is to the true value of the quantity being
  measured.
• ?Who is more accurate when measuring a book that
  has a true length of 17.0cm?
• Andrea ?
• 17.0cm, 16.0cm, 18.0cm, 15.0cm
• Amy
• 15.5cm, 15.0cm, 15.2cm, 15.3cm

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What is Precision?

• Precision a measure of how close a series of
  measurements are to one another. A measure of how
  exact a measurement is.
• ?Who is more precise when measuring the same
  17.0cm book?
• Andrea
• 17.0cm, 16.0cm, 18.0cm, 15.0cm
• Amy ?
• 15.5cm, 15.0cm, 15.2cm, 15.3cm

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Rules For Significant Figures

• Significant figures are used for measured numbers
  and for numbers derived from measurements does
  not include
• definitions (ex. 1000ml1L) or
• counting numbers (ex. 1,2,3 etc)

10 mm 1cm (2 significant figures) 100cm 1m
(3 significant figures) 1000g 1kg (4
significant digits)
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• 2. Digits from 1-9 are always significant.

Ex. 2342 4 significant figures 25 2
significant figures 23.42 4 significant
figures
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• 3. Zeros between two other significant digits are
  always significant.
• Ex. 5 055 g 4 significant figures
• 207 ml 3 significant figures

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• 4. One or more additional zeros to the right of
  both the decimal place and another significant
  digit are significant.
• Ex. 5.00 3 significant figures
• 50.05 4 significant figures
• 50.50 4 significant figures

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• 5. Zeros used solely for spacing the decimal
  point (placeholders) are not significant.
• Ex. 0.007 (1 significant figure)
• 1000 ( 1 significant figure)
• 0.015 ( 2 significant figures)

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• 6. Exact numbers have an infinite number of
  significant digits but they are generally not
  reported. All non zero digits are significant.
• Ex. 2 ( 1 significant figure)
• 453 (3 significant figures)

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Its Your Turn To Try!?

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• How many significant figures do the following
  numbers have?

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1) 1234 _____ 2) 0.023 _____ 3) 890 _____ 4) 91010 _____ 5) 9010.0 _____ 6) 1090.0010 _____ 7) 0.00120 _____ 8) 0.00030 _____ 9) 1020010 _____ 10) 72 _____ 11) 1000 _____ 12) 918.010 _____ 13) 0.0001 _____ 14) 0.00390 _____ 15) 8120 _____
1.) 4 2.) 2 3.) 2 4.) 4 5.) 5 6.) 8 7.)
3 8.) 2 9.) 6 10.)2 11.) 1 12.) 6 13.)
1 14.) 3 15.) 3
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Assignment

• Determine the number of significant digits in the
  following numbers.
• 1) 5600 _____
• 2) 45.00_____
• 3) 105.0_____
• 4) 0.00565_____
• 5) 0.005400_____
• 6) 89.543_____
• 7) 5, 056, 300_____
• 8) 95.0540_____
• 9) 93, 000, 000_____
• 10) 21.35_____